Biomedical subjects

L D Erickson

Publications and source records attributed to L D Erickson.

10 recordsLinked to original sources

PubMed2001

Murine B1 B cells require IL-5 for optimal T cell-dependent activation.

T helper cell-driven activation of murine B cells has been shown to depend upon CD40-CD40 ligand (CD40L) interactions and a defined set of cytokines. These observations are primarily based on the use of conventional B cells obtained from the spleen. Therefore, it is presently unclear whether all mature B cell subsets found in the mouse have an equal dependence upon CD40-CD40L interactions and use the same T cell-derived cytokines. The present study tested the response of splenic follicular and marginal zone as well as peritoneal B2 and B1 B cells to Th cell stimulation. Splenic and peritoneal B cell subsets were sort purified based on CD23 expression, and cultured with rCD40L and cytokines or Th2 cells. The results demonstrate that follicular, marginal zone, and peritoneal B2 B cells require CD40-CD40L interactions and preferentially use IL-4 for optimal proliferation, differentiation, and isotype switching. In contrast, peritoneal B1 B cells use IL-5 in conjunction with CD40-CD40L interactions for maximal Th cell-dependent responses. Furthermore, B1 B cells are capable of proliferating, differentiating, and isotype switching in the absence of CD40-CD40L interactions. B1 B cells are able to respond to Th2 clones in the presence of anti-CD40L mAb as well as to Th2 clones derived from CD40L(-/-) mice. The CD40-CD40L-independent response of B1 B cells is attributable to the presence of both IL-4 and IL-5, and may explain the residual Ab response to T cell-dependent Ags in CD40L- or CD40-deficient mice, and in X-linked hyper-IgM (X-HIM) patients.

Animals↗

PubMed2000

B cell immunopoiesis: visualizing the impact of CD40 engagement on the course of T cell-independent immune responses in an Ig transgenic system.

This study tracks the fate of antigen-reactive B cells through follicular and extrafollicular responses and addresses the function of CD40 in these processes. The unique feature of this system is the use of transgenic B cells in which the heavy chain locus has been altered by site-directed insertion of a rearranged V(H) DJ(H) exon such that they are able to clonally expand, isotype-switch and follow a normal course of differentiation upon immunization. These Ig transgenic B cells when adoptively transferred into non-transgenic (Tg) mice in measured amounts expanded and differentiated distinctively in response to T cell-independent (TI) or T cell-dependent (TD) antigens. The capacity of these Tg B cells to faithfully recapitulate the humoral immune response to TI and TD antigens provides the means to track clonal B cell behavior in vivo. Challenge with TI antigen in the presence of agonistic anti-CD40 mAb resulted in well-defined alterations of the TI response. In vivo triggering of Tg B cells with TI antigen and CD40 caused an increase in the levels IgG produced and a broadening of the Ig isotype profile, characteristics which partially mimic TD responses. Although some TD characteristics were induced by TI antigen and CD40 triggering, the Tg B cells failed to acquire a germinal center phenotype and failed to generate a memory response. Therefore, TD-like immunity can be only partially reconstituted with CD40 agonists and TI antigens, suggesting that there are additional signals required for germinal center formation and development of memory.

Adoptive Transfer↗

PubMed1996

Minimal stimulation achieves pregnancy rates comparable to human menopausal gonadotropins in the treatment of infertility.

OBJECTIVE: To examine the effectiveness of a novel clomiphene citrate (CC) and hMG combination protocol ("minimal stimulation") for controlled ovarian hyperstimulation. Minimal stimulation consists of administering 100 mg/d CC for 5 days followed by a single dose of 150 IU hMG. The results of this analysis are compared with those of an hMG-alone protocol. In vitro fertilization-embryo transfer and donor insemination patients are excluded from this analysis. DESIGN: Retrospective review of minimal stimulation and hMG cycles from January 1, 1989 to December 31, 1992. SETTING: Tertiary care center reproductive endocrinology and infertility clinic. PATIENTS: Two hundred thirty-two women who underwent 549 treatment cycles. MAIN OUTCOME MEASURES: Clinical and multiple pregnancy rates (PRs) and medication costs. RESULTS: Sixty-one women received 106 cycles of minimal stimulation and 183 received 443 cycles of hMG. Although subject groups were not assigned randomly, multivariate analysis detected no significant differences between the treatment groups. The total ampules of hMG required differed significantly (2.0 for minimal stimulation versus 16.8 +/- 8.5 [mean +/- SD] for hMG). Pregnancy rates and multiple gestation rates were similar. Medication expense of minimal stimulation is 21% that of the hMG protocol. CONCLUSIONS: Minimal stimulation is as effective as hMG in the population examined. The comparable PRs and decreased medication costs of minimal stimulation justifies further evaluation of its role in the treatment of infertility.

Adult↗

PubMed1996

Differential expression of CD22 (Lyb8) on murine B cells.

Previous studies have established the distribution, biochemistry and functional attributes of human CD22, a B cell-restricted glycoprotein. Recently, molecular cloning of the murine CD22 equivalent revealed this molecule to be the same as the previously described Lyb8 alloantigen. Using the anti-Lyb8 mAb Cy34.1.2, the present report documents the expression patterns of CD22 within the murine B cell compartment. The results demonstrate that in the bone marrow, murine CD22 is absent on the surface of pro-B cells, pre-B cells and newly emerging IgM+ B cells. CD22 is present at a low density on immature IgMhi B cells and fully expressed on mature recirculating B cells. In the periphery, murine CD22 is expressed at mature levels on all B cell subsets including follicular, marginal zone, B1 and switched B cells. Further studies showed CD22 to be retained on activated murine B cells for extended periods. Finally, in combination with CD23 and heat stable antigen, CD22 can be used to delineate the immature splenic B cells, and distinguish them from follicular and marginal zone cells. Together, the results demonstrate murine CD22 to be a useful pan marker for all mature B cell subsets.

Animals↗

PubMed1995

Transverse vaginal septum associated with tubal atresia.

Transverse vaginal septum is a defect of vertical fusion during embryogenesis of the vagina. The estimated incidence is 1 per 30,000 to 84,000 women. It is infrequently associated with genitourinary tract, gastrointestinal tract, musculoskeletal, and cardiac malformations. Previous reports of transverse vaginal septum have included unilateral absence of the fallopian tube and ovary and absence of the proximal portion of the fallopian tube. This report describes bilateral tubal atresia associated with a transverse vaginal septum. A 17-year-old nulligravida sought medical assessment because of primary amenorrhea and cyclic pelvic pain. Physical examination revealed a blind vaginal pouch and a tender pelvic mass. Radiologic studies showed a transverse vaginal septum 1.5 cm distal to the cervix. The septum was resected with laparoscopic guidance, and bilateral fallopian tubal atresia was noted. The pelvis was otherwise normal. Patients commonly have a pelvic or abdominal mass, pain, and amenorrhea at time of expected menarche. Surgical resection is the treatment of choice. Postoperative dilation may be necessary to prevent restenosis. Outlook for pregnancy is encouraging despite a higher than normal incidence of spontaneous abortion and endometriosis in such patients.

Adolescent↗

PubMed1994

Cyclophosphamide, cisplatin, and leuprolide acetate in patients with debulked stage III or IV ovarian carcinoma.

A phase II study of cyclophosphamide, cisplatin, and leuprolide acetate after debulking of stage III or IV ovarian carcinoma was conducted in 33 patients through a cooperative group study involving 11 institutions. The intent was to determine whether the addition of a gonadotropin-releasing hormone analogue would alter the response rates and toxicity profile of cyclophosphamide and cisplatin in patients with advanced ovarian cancer. Twenty-nine patients completed all 6 planned cycles. Of the 19 patients who had second-look laparotomy, 12 had persistent disease and 7 were negative for disease. The use of a gonadotropin-releasing hormone with combined chemotherapy did not alter the toxicity profile or the effectiveness of chemotherapy when comparisons were made with historical controls.

Antineoplastic Combined Chemotherapy Protocols↗

PubMed1993

A successful assisted reproductive technology satellite program.

A satellite program was implemented to provide IVF to interested infertile couples living in a five-state area. Thirty-six gynecologists were established as satellite sites after appropriate screening and training. No attempt was made to interchange reference serum specimens between laboratories. Patients were seen at Mayo Clinic for an initial consultation and did not return until the ovulatory dose of hCG was administered. There was no difference in cancellation, clinical pregnancy, and delivery rates between satellite and central unit monitored patients. Satellite monitoring decreases patient inconvenience and time away from home and the workplace without compromising cycle outcome.

Delivery of Health Care↗

PubMed1993

A novel ovarian stimulation protocol for use with the assisted reproductive technologies.

OBJECTIVE: To determine whether a new ovarian stimulation protocol termed "minimal stimulation" provides pregnancy rates (PRs) comparable with those in a conventional full stimulation protocol for patients undergoing assisted reproductive technologies (ART). DESIGN: Prospective, nonrandomized study of patients in minimal stimulation or full stimulation, followed by standard IVF and zygote intrafallopian transfer or uterine-ET. SETTING: The ART program of the Mayo Clinic, Rochester, Minnesota. PATIENTS: Women (n = 120) 42 years of age or younger with serum day 3 FSH level < or = 15.0 mIU/mL (conversion factor to SI unit, 1.0), normal thyroid-stimulating hormone and PRL levels, normal endometrial cavity as observed on hysterosalpingogram, and partners with a normal semen analysis. INTERVENTIONS: Oral clomiphene citrate, hMG, oocyte retrieval, IVF-ET. MAIN OUTCOME MEASURES: Cancellations, implantation, pregnancy. RESULTS: The cancellation rate was not significantly higher in minimal stimulation (25.8%) than in full stimulation (14.1%). Minimal stimulation cycles yielded fewer oocytes per aspiration (3.4 +/- 1.6) than full stimulation (10.1 +/- 5.4). There was no difference in the implantation rates per ET (minimal stimulation, 16.4%; full stimulation, 13.3%) or overall clinical PRs per retrieval (minimal stimulation, 31%; full stimulation, 42%). CONCLUSIONS: Minimal stimulation for IVF is less expensive than full stimulation and minimizes monitoring and patient discomfort. In addition, it produces acceptable PRs and represents an attractive alternative to select patients undergoing ART.

Adult↗

PubMed1990

Synthetic alpha-subunit peptides stimulate testosterone production in vitro by rat Leydig cells.

The glycoprotein hormones (LH, hCG, FSH, and TSH) have a common 92-amino acid alpha-subunit which is noncovalently linked to a hormone-specific beta-subunit. Synthetic peptides of the alpha-subunit have been shown to inhibit binding of [125I]iodo-hCG to rat ovarian membrane and [125I]iodo-TSH to human thyroid membrane preparations. Synthetic overlapping peptides of the alpha-subunit of hCG were prepared by solid phase techniques and tested in a standard in vitro rat Leydig cell bioassay. Three regions in the alpha-subunit (alpha 1-15, alpha 30-45, and alpha 71-85) were found to stimulate testosterone production. All three regions correlate with inhibition of hCG binding to ovarian receptors, but subtle differences exist between the binding sites and effector sites. These data indicate that the glycoprotein alpha-subunit has intrinsic bioactivity.

Amino Acid Sequence↗

PubMed1989

GnRH analogues in the treatment of endometriosis.

Modifications of the native gonadotropin-releasing hormone (GnRH) decapeptide have led to longer-acting compounds with increased binding ability. Pharmacologic doses of agonists result in suppression of ovarian estradiol production to levels similar to oophorectomized patients. The resultant hypoestrogenism is associated with regression in endometrial implant size. Both subjective and objective clinical improvement have been reported. Recent studies document that a reversible state of hypogonadism is effective treatment for endometriosis.

Buserelin↗